On Parubenzole, ami un the Isomers of Turpentine. 523 



of it (being without action on polarized light), boils at the same 

 point. 



The hydrocarbons which constitute or accompany the essences of 

 Athamanta, birch, Borneo camphor, wintergreen, juniper, parsley, 

 savine, thyme, and valerian, together with tolene from balsam of 

 Tolu, have the composition of oil of turpentine, and boil at the 

 same temperature, 160'. To this list must be added the hy<lro- 

 carbon from oil of anise, which, whc^n freed from the last traces 

 of the oxygenated essence by distillation off sodium, boils steadily 

 at 160°, and seems to resemble oil of turpentine very closely, 

 although it has somewhat of the odour of lavender. It is most 

 probable that many of the oils just enumerated are actually 

 identical with ordinary turpentine. 



Besides these twelve oils from different sources, which are 

 either isomeric or identical with turpentine, there are at least six 

 other oils of the same composition which boil at or near 175°. 

 These are the hydrocarbons from camomile, caraway, citron, 

 elemi and rosemary, and also a modification of turpentine known 

 as isoterebenthene. If the boiling-point (143°) assigned by 

 Ettling to the turpentine of clove-oil be correct, we have repre- 

 sentatives of three classes of isomeric turpentines, the boiling- 

 points of which exhibit very singular relations. One class of 

 these hydrocarbons, obtained from seven sources, has a boiling- 

 point of 175°; a second class from thirteen sources, one of 160°; 

 and we perhaps possess a third class, represented by one member 

 at present, which boils at 143°. The difference between the 1st 

 and 2nd class is thus 15° ; between the 2nd and 3rd 17°. It is 

 remarkable that nearly the same difference (16°'7) occurs between 

 the boiling-points of parabenzole and benzole. 



An observation which I have lately made tends to show that 

 this coincidence is not merely accidental. On fractionating a 

 portion of coal-naphtha, which, after purification with sodium, 

 had distilled over iii the 4th rectification between 115° and 125°, 

 I noticed that I'oths of the liquid passed over between 119° and 

 120°. On repeating the operation, the boiling-point of this 

 portion was constant at 119°"5. Butyle, C^IP, C^H^, has been 

 ascertained by Mr. Greville Williams to boil at this temperature; 

 and I at first suspected the liquid under examination to be that 

 substance. But the liquid boiling at 119°"5 dissolves jjcrfectly 

 in cold nitric acid, yielding a compound apparently identical with 

 nitrotoluole : again, when it is treated with fuming sulphuric 

 acid, diluted vvith water, and then saturated with carbonate of 



barium, it yields a difficultly crystallizable barium salt, contain- 

 ing the same |)erccntagc of barium as tlie sul))hotoluolate of that 



metal. 1 hope to examine this hydrocarlxtn more thoroughly ; 



in the meantime I would hazard the conjecture that it stands to 



